VM start command race condition

When a VM is started with the `hostmgr start` command, a race condition exists where:
1. The VM is requested to be started
2. The server (`hostmgr-helper`) returns that the VM has started
3. The client (`hostmgr`) then [grabs the IP](https://github.com/Automattic/hostmgr/blob/82fbaeb6b5d47c89a24fc7e3e80736e05876c6eb/Sources/libhostmgr/Platforms/VMManager.swift#L112) (if told to) of the new VM and [confirms that SSH is available](https://github.com/Automattic/hostmgr/blob/82fbaeb6b5d47c89a24fc7e3e80736e05876c6eb/Sources/libhostmgr/Platforms/VMManager.swift#L113)

It's possible for the VM to be removed between steps 2 and 3 if an outside call is made to `hostmgr vm stop`. An improvement could be for the second step to return this information upon creation synchronously and remove step 3.

Start in Sources/libhostmgr/Platforms/VMManager.swift at the IP lookup and SSH confirmation around lines 112–113, then trace the hostmgr start response from hostmgr-helper and the hostmgr vm stop path. Reproduce the timing window if possible and define done as preventing a VM from disappearing between the start response and follow-up checks, with the creation response carrying the needed information synchronously.

Written by the indexing model from the issue text.